U.S. President Donald Trump is again facing questions about his ties to Russia, amid new allegations that another member of his inner circle had contact with Russian officials.

Attorney General Jeff Sessions has denied reports that suggest he spoke with Sergey Kislyak, Russia's ambassador to the U.S., last year. During his confirmation hearings, Sessions said he didn't have any contact with Russian officials during the presidential campaign.

Sessions is the latest Trump associate to face questions about contact with Russia, a country that has been accused of meddling in last year's election. Trump has shifted his stance regularly, heaping praise on Russian President Vladimir Putin one moment while being aloof about their relationship the next.

Here's a timeline of the allegations and investigations into Trump's relationship with the Kremlin.

July 22, 2016: More than 19,000 emails from Democratic Party officials are leaked and posted on the document disclosure site Wikileaks ahead of the Democratic National Convention. The FBI a year earlier had told the Democratic National Committee that Russian hackers had likely gained access to its computer network.

Trump calls on Russia to hack Clinton's email during news conference2:07

July 27, 2016: During a press conference in Miami, Trump calls on Russia to seek out missing emails from rival Democratic candidate Hillary Clinton's private email server. "Russia, if you're listening, I hope you're able to find the 30,000 emails that are missing," Trump says. "I think you'll be rewarded mightily by our press!"

Aug. 14, 2016: Paul Manafort, Trump's campaign chair, resigns. The New York Times earlier reported that Manafort had received $12.7 million US in undisclosed payments from a pro-Russian political party in Ukraine. Manafort denies the allegations.

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Republican nominee Donald Trump rejected Democratic candidate Hillary Clinton's suggestion that Russian hackers had leaked her party's emails. (Rick Wilking/Reuters)

Sept. 26, 2016: In the first debate, Trump casts doubt on who conducted the email hack, saying, "[Hillary is] saying Russia, Russia, Russia, but I don't — maybe it was. I mean, it could be Russia, but it could also be China. It could also be lots of other people. It also could be somebody sitting on their bed that weighs 400 pounds, OK?"

Oct. 7, 2016: The Department of Homeland Security and the Office of the Director of National Intelligence on Election Security release a joint statement saying they believe the Russian government directed the email hack. "We believe, based on the scope and sensitivity of these efforts, that only Russia's senior-most officials could have authorized these activities," the statement says.

Trump, Clinton clash over Russia and WikiLeaks0:36

Oct. 20, 2016: Trump and Clinton exchange barbs in their third debate. Trump says he believes Putin has no respect for Clinton, to which she responds that the Russian president would obviously prefer to have a puppet as the U.S. President. "It is pretty clear you won't admit that the Russians have engaged in cyber attacks against the United States of America. That you encouraged espionage against our people. That you are willing to spout the Putin line, sign up for his wish list, break up NATO, do whatever he wants to do," she says. "And that you continue to get help from him because he has a very clear favourite in this race."

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Trump said Russia hacking didn't influence the outcome of the 2016 election. (Richard Drew/Associated Press)

Dec. 11, 2016: Trump denies suggestions that Russia helped him win the election. U.S. President Barack Obama orders a review of the election hacking.

Dec. 16, 2016: Obama says Putin knew about the hacking. "Not much happens in Russia without Vladimir Putin," he asserts. On the same day, the FBI confirms that Russia meddled in the election in a bid to help Trump.

Dec. 29, 2016: Washington announces sanctions on Russia and expels 35 diplomats after U.S. intelligence agencies release a report about the hacking into the DNC computer network. A day later, Trump praises Putin for not retaliating by expelling U.S. diplomats from Russia.

Jan. 6, 2017: The Central Intelligence Agency, the FBI and the National Security Agency release a report that says Putin tried to discredit Clinton in a bid to help Trump win the presidency. Trump responds, saying the hacking attempt did not influence the outcome of the election.

Jan. 11, 2017: At his first press conference as president-elect, Trump faces questions about a secret intelligence file that allegedly contains compromising personal and financial information. The dossier reportedly says that Russia had collected potentially embarrassing details about Trump and suggests he's accordingly vulnerable to blackmail. Trump denies the claims as "fake news."

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At his first press conference as president-elect, Trump was confronted with questions about a report that suggested Russian officials had collected compromising personal information about him. (Seth Wenig/Associated Press)

Jan. 27, 2017: Trump says he hopes the U.S. and Russia will enjoy a "fantastic relationship" during a press conference. "As far as, again, Putin and Russia, I don't say good, bad or indifferent. I don't know the gentleman. I hope we have a fantastic relationship. That's possible and it's also possible that we won't. We will see what happens," he says.

Feb. 5, 2017: Trump defends Putin in an interview with Fox's Bill O'Reilly, saying he respects him. "I respect a lot of people, but that doesn't mean I'm going to get along with him. He's a leader of his country. I say it's better to get along with Russia than not. And if Russia helps us in the fight against ISIS, which is a major fight, and Islamic terrorism all over the world — that's a good thing."

Michael Flynn

Michael Flynn resigned from his post as national security adviser amid suggestions that he had not fully disclosed the extent of his contact with Russia's ambassador to the U.S. (Win McNamee/Getty Images)

Feb. 13, 2017: Michael Flynn, Trump's national security adviser, resigns, amid allegations that he made improper contact with Russia and misled Vice-President Mike Pence. Flynn acknowledged speaking with Russian Ambassador Sergey Kislyak in late December though he denied discussing sanctions. The Washington Post reports that former acting attorney general Sally Yates in January contacted the White House and warned there were inconsistencies in Flynn's accounts, saying he may be vulnerable to Russian blackmail.

Feb. 15, 2017: CNN reports that Paul Manafort, Trump's former campaign manager, was frequently in touch with senior Russian officials during the campaign. Manafort denies the allegations, saying "I don't remember talking to any Russian officials, ever."

March 1, 2017: The Washington Post alleges U.S. Attorney General Jeff Sessions had two conversations with the Russian ambassador to the U.S. last year. Sessions, who said during his confirmation hearings that he hadn't spoken with Russia during the campaign, calls the report false.

March 2, 2017: Sessions announces that he will recuse himself from any investigations into interference with the 2016 presidential election. However, he did not confirm that any investigation is currently underway. The attorney general also said he did not mislead Congress during his confirmation hearing because the meetings he had with the Russian ambassador were in his role as senator and not as a campaign surrogate. 

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U.S. Attorney General Jeff Sessions said during his confirmation hearings that he didn't have contact with Russian officials. (Yuri Gripas/Reuters)

March 3, 2017: White House spokesperson Hope Hicks confirms Trump's son-in-law and adviser, Jared Kushner, and Flynn met with the Russian ambassador at Trump Tower in December. The encounter was described as a brief courtesy meeting.

March 4, 2017: Trump accuses former president Barack Obama of having wiretapped Trump Tower during the presidential campaign. He does not offer evidence to support his claim. Obama's spokesman denies the allegation.

March 16, 2017: Elijah Cummings, the ranking Democrat on the House Oversight Committee, says that Flynn in 2015 received more than $30,000 for a speech he made in Moscow. Cummings says that RT TV-Russia, the state broadcaster, paid Flynn.